Digital asset transaction and privacy protection method based on alliance chain multi-party computing

Abstract

The invention provides a digital asset transaction and privacy protection method based on alliance chain multi-party computing, and relates to the technical field of alliance chains, and the method specifically comprises the steps of creation and issuing of digital assets, transaction of the digital assets, recharging of a user account and change of a user mechanism, and is realized based on a digital asset transaction platform. The digital asset transaction platform comprises a user client, a background server and an alliance chain platform server; a common user submits asset information to the background server for processing through the user client, or performs asset information auditing operation through an institution administrator or a super administrator; transferring the processed asset data to a corresponding mechanism node for management, and storing the processed asset data in a database of a corresponding mechanism; the alliance chain platform server is composed of a digital asset intelligent contract, a block chain node and a member service node, and the digital asset intelligent contract defines data structures of users and assets and specifies specific business processing rules of asset issuing, user registration and asset transaction.

Description

Technical Field

[0001] The present invention relates to the field of alliance chain technology, and in particular to a digital asset transaction and privacy protection method based on alliance chain multi-party computing. Background Art

[0002] With the development of society, people's wealth is no longer limited to physical assets. The digital era has brought new forms of assets, such as digital points, electronic currency and electronic equity. Unlike traditional physical assets, digital assets are portable and highly divisible, and can be traded and circulated on the Internet in a digital form.

[0003] Initially, digital assets were more in the form of digital currencies, issued using blockchain technology, such as Bitcoin, Peercoin, etc. However, through in-depth research on blockchain technology, especially the introduction of smart contract technology, blockchain technology has realized the processing of complex business logic, and has been widely used in cross-border payments, supply chain finance and other fields; smart contracts are transparent to relevant entities and have unified contract rules, which can reduce the distrust between enterprises.

[0004] However, the existing digital asset trading system faces a series of challenges. According to the current research, the existing digital asset (digital rights) platforms in China have not yet opened private platforms, do not support multiple transfer transactions, and have weak asset liquidity; most of them rely on decentralized systems and lack unified specifications and interfaces, which leads to the problem that digital assets are difficult to circulate smoothly between different institutions, limiting the flexibility and liquidity of assets; the electronic database of the existing system is vulnerable to tampering and attack, which may lead to security risks of users' digital assets and cause users' concerns about the security of digital assets.

[0005] In addition, data privacy has also had a great impact on people's work and life. Social media and various traditional centralized applications continue to collect personal data, causing users to worry about the risk of personal privacy data leakage, and people are reluctant to provide their data to others for commercial use. However, only mobile data is valuable, and service providers can only provide more accurate personalized services based on the data provided by users, which has formed a contradiction invisibly.

[0006] Although blockchain is currently widely used in the field of digital assets, there is still a need to better protect user data privacy in actual application.

[0007] First, the consensus mechanism of the public chain is usually more complicated, which makes it more difficult to reach consensus and also affects the speed of data processing. This is particularly evident when dealing with large-scale, high-frequency digital asset transactions. By limiting participating nodes and adopting a consensus algorithm that is more suitable for specific application scenarios, the consortium chain can significantly improve data processing speed and transaction efficiency while ensuring a certain degree of security.

[0008] Second, although the alliance chain channel can protect privacy by limiting data access, this approach does not fundamentally solve the problem. Risks such as internal personnel leakage and hacker attacks still exist. Secure multi-party computing technology can perform collaborative computing without exposing the original data, thereby achieving secure verification and settlement of digital asset transactions while protecting privacy. This technology can make up for the shortcomings of the alliance chain in privacy protection and provide more comprehensive security protection.

[0009] Third, the weak liquidity of digital assets on domestic platforms is an urgent problem to be solved. By building a network environment composed of multiple trusted nodes, the alliance chain can promote the safe and efficient circulation of digital assets within a specific range. At the same time, the application of secure multi-party computing technology can also reduce transaction costs and improve transaction efficiency.

[0010] Therefore, the introduction of alliance chain and secure multi-party computing technology can effectively solve the problems of difficult consensus and slow processing speed of public chain, make up for the shortcomings of alliance chain in privacy protection, and improve the liquidity of digital assets. The application of these technologies will help standardize the digital asset transaction process, improve the security and privacy protection level of transactions, and promote the healthy development of the digital economy. Summary of the invention

[0011] In view of the deficiencies in the prior art, the present invention provides a digital asset transaction and privacy protection method based on alliance chain multi-party computing.

[0012] A digital asset transaction and privacy protection method based on alliance chain multi-party computing, implemented on a digital asset transaction platform, wherein the digital asset transaction platform includes a user client, a background server, and an alliance chain platform server;

[0013] Ordinary users submit asset information to the backend server for processing through the user client, or the asset information is reviewed by the institution administrator or super administrator; the processed asset data will be transferred to the corresponding institution node management and stored in the database under the corresponding institution; the alliance chain platform server is composed of digital asset smart contracts, blockchain nodes and member service nodes. The digital asset smart contracts define the data structure of users and assets, and stipulate the specific business processing rules for asset issuance, user registration and asset transactions. The blockchain nodes provide blockchain services, receive business requests from the transaction background and conduct transaction consensus; the member service nodes rely on the complete member identity management mechanism encapsulated by the alliance chain platform server to provide member identity information identification and management functions for the backend server.

[0014] The super administrator maintains contracts and alliance organizations, uploads and deploys smart contracts, queries the historical records of smart contract deployment, and registers new alliance organizations and organization administrators in the digital asset trading platform;

[0015] The said institution administrator manages assets and ordinary users, and manages the ordinary user information, digital asset status, and transaction records of the institution;

[0016] The ordinary user registers and logs in through the digital asset trading platform, and conducts digital asset transactions within or across institutions on the digital asset trading platform;

[0017] The digital asset trading platform relies on the distributed ledger of the alliance chain, uses a state database, stores digital asset information in the form of key-value pairs, and stores asset information change records in the form of blocks on the blockchain. The data structure includes two types of user information and asset information; user information defines user account, authority, affiliated organization, and asset quantity information; digital asset information defines the ID, affiliated organization, owner, and asset name information of the digital asset; asset information is fragmented, and the asset information is split into multiple asset units according to attribute categories, and data sharding technology is used to disperse the data of multiple asset units after splitting to multiple nodes or storage devices;

[0018] The user client and backend server of the digital asset trading platform both include user management, contract management, asset management and transaction processing modules.

[0019] The user management module implements the functions of registration, recharge, and transaction record query information maintenance for institutions and ordinary users; the default setting is that the information of the super administrator is directly written into the transaction background and smart contract. The super administrator performs registration operations on the institutions newly joining the alliance and records the institutional information into the database; in the process of registering institutional administrators, it is necessary to extract the institutional ID and institutional administrator data and write them into the blockchain together; ordinary users directly submit a registration form application, which is reviewed by the background and submitted to the blockchain to complete the registration. After completing the registration, the account is recharged and the personal information is improved. When ordinary users want to change their institutions, the change must be completed after the approval of the original institution and the administrator of the new institution; if the institution wants to withdraw from the alliance chain network, it must notify all users in the institution to complete the transfer to the new institution within the specified time limit, and implement the copyright management policy of the original institution during the transition period. Users may reselect other institutions. It is expected that users who do not select new institutions will be changed to the state of no institution by default, and need to reapply to join the new institution to participate in asset trading, and will not enjoy the transition period execution policy.

[0020] The contract management module implements the functions of uploading, deploying and querying the deployment history of smart contract files. When specific business rules change, the smart contract program needs to be rewritten according to the new rules and deployed to the alliance chain platform through the super administrator; uploading smart contracts is the process of uploading the written contract program file to the file server and recording the version number and business type information to the database; deploying smart contracts is the process of calling the blockchain smart contract deployment interface to deploy the contract file to the alliance chain platform. After successful deployment, the alliance chain platform will use the new contract program for transaction processing; deployment history query is the super administrator querying the historical records of contract deployment based on the background database records;

[0021] The asset management module is responsible for the issuance and management of digital assets. The assets submitted by the creator user are allowed to be issued online after being reviewed and approved by the administrator of the institution. The institution administrator issues digital assets in the name of the institution. Once the asset information is released, it will not be allowed to be changed, and only transactions and transfers can be realized.

[0022] The transaction processing module is responsible for receiving transaction requests for intra-institutional transactions and cross-institutional transactions, performing request verification, and transmitting transaction requests, and providing feedback to the user after obtaining the processing results; wherein, before the cross-institutional transaction process is carried out, user information needs to be queried and verified on the blockchain, and during the cross-institutional transaction process, it is necessary to implement and deduct the relevant policies of the institution where the original owner of the digital asset is located regarding the asset management and maintenance fee rate.

[0023] The digital asset trading platform stipulates and restricts the behaviors in the trading process, including:

[0024] 1. The number of daily transactions of a single digital asset between ordinary users shall not exceed 3 times;

[0025] 2. In principle, the amount by which the asset seller adjusts the transaction price of a single digital asset shall not exceed 20% of the current price. When the price adjustment exceeds 20%, the seller must provide the asset seller’s institution management with a price adjustment explanation and materials, and obtain approval from the institution’s administrator.

[0026] 3. The asset seller may adjust the transaction price of a single digital asset no more than twice a month;

[0027] A digital asset transaction and privacy protection method based on alliance chain and secure multi-party computing, implemented based on the aforementioned digital asset transaction platform, specifically including the creation and issuance of digital assets, the transaction of digital assets, the recharge of user accounts and the change of user institutions;

[0028] The creation and issuance of the digital assets specifically include the following steps:

[0029] Step A1: The asset creator submits digital asset issuance information to the administrator of the institution to which he belongs;

[0030] Step A2: After receiving the digital asset issuance information, the institution administrator will review it. If the issuance information is reviewed and found to be correct, step A3 will be executed. If there are problems with the issuance information review, the institution administrator will return the asset issuance information to the asset creator for revision. After the revision, step A1 will be executed.

[0031] Step A3: The institution administrator checks the issuance status of the digital asset issuance information. If the digital asset has not been issued, the institution administrator submits the digital asset issuance information to the platform. If the digital asset has been issued, the institution administrator returns the asset issuance information to the asset creator for re-modification. After the modification, execute step A1;

[0032] Step A4: After receiving the digital asset issuance information submitted by the institution administrator for review, the platform calls the smart contract asset management interface to process the asset issuance information;

[0033] Step A5: The platform stores the processed asset issuance information into the status database;

[0034] Step A6: Digital assets are issued successfully.

[0035] The transaction of the digital asset specifically includes the following steps:

[0036] Step B1: The asset owner or institution issues digital assets, and the asset buyer submits a purchase request to the platform;

[0037] Step B2: After receiving the asset purchase request submitted by the asset purchaser, the platform determines whether the asset purchaser and the institution to which the asset to be purchased belongs to the same institution; if they do, the platform transfers the intra-institutional transaction request and the asset purchase request to the institution to which the asset belongs and executes step B3; if they do not, execute step B4;

[0038] Step B3: After the institution to which the asset belongs receives the intra-institutional transaction request and asset purchase request transferred from the platform, it executes the digital asset transaction within the institution and executes step B5;

[0039] Step B4: Execute cross-institution digital asset transactions;

[0040] Step B4.1: The platform retrieves the cross-institutional transaction policy fee standard information of the institution to which the asset is purchased, and transfers the standard information, the cross-institutional transaction request and the asset purchase request to the institution to which the asset belongs;

[0041] Step B4.2: After the institution to which the asset belongs receives the cross-institutional transaction policy fee standard information, cross-institutional transaction request and asset purchase request transferred by the platform, it executes step B5;

[0042] Step B5: The institution to which the asset belongs checks whether the balance of the asset buyer's account is sufficient. If the balance meets the asset transaction price, step B6 is executed. If the balance does not meet the asset transaction price, the asset transaction fails and the user should recharge the account.

[0043] Step B6: The institution to which the asset belongs submits information such as the asset purchase request and transaction request to the platform;

[0044] Step B7: After receiving the asset request, transaction request and other information submitted by the institution to which the asset belongs, the platform calls the smart contract asset transaction interface to process the asset transaction information;

[0045] Step B8: The platform stores the processed asset transaction information into the status database;

[0046] Step B9: Digital asset purchase is successful.

[0047] The recharging of the user account specifically includes the following steps:

[0048] Step C1: The user submits an account recharge request to the platform to perform payment operations;

[0049] Step C2: The platform receives the account recharge request submitted by the user and waits for the payment result from the payment platform;

[0050] Step C3: When the payment result of the payment platform shows that the payment is successful, execute step C4; when the payment result of the payment platform shows that the payment fails, the account recharge fails;

[0051] Step C4: The platform calls the smart contract user management interface to process the account recharge request and payment success information;

[0052] Step C5: The platform stores the processed account recharge information into the status database;

[0053] Step C6: Account recharge is successful.

[0054] The change of the user organization specifically includes the following steps:

[0055] Step D1: User organization change application includes two situations, namely, ordinary users submit change applications, and execute step D1.1; organization withdrawal adjustment ordinary user organization change, execute step D1.2;

[0056] Step D1.1: The user submits an application for change of organization, that is, the user submits the application for change of organization to the administrator of the organization to which the user currently belongs, and executes step D3;

[0057] Step D1.2: When an institution applies to withdraw from the platform, it must reach an agreement with the institution that will take over the platform. The withdrawing institution will submit the agreement to the platform and execute step D2;

[0058] Step D2: After the exiting institution and the undertaking institution reach an agreement and submit it to the platform, execute steps D2.1, D2.2 and D2.3 in sequence;

[0059] Step D2.1: After receiving the agreement submitted by the exiting institution, the platform will file it and send the result of the filing completion to the exiting institution;

[0060] Step D2.2: After the exiting institution receives the record completion result from the platform, it will issue a notice to all users in the institution, and the users will choose to implement the transitional policy or apply for a change of institution;

[0061] Step D2.3: When the user chooses to implement the transitional policy, the user submits a request to the platform to change the transitional policy implementation agency, and executes step D5. When the user chooses to apply for agency change, execute step D1;

[0062] Step D3: After receiving the organization change request submitted by the user, the administrator of the current organization of the user will review whether the user meets the transfer-out conditions. If the review is passed, the administrator of the current organization of the user will transfer the organization change request to the organization to which the user intends to transfer, and execute step D4. If there is a problem in the review, the organization administrator will return the organization change request information to the user for inspection;

[0063] Step D4: After receiving the change of institution application request from the original institution of the user, the administrator of the institution to which the user intends to transfer will review whether the user meets the transfer-in conditions. If the review is passed, the administrator will submit the change of institution application request to the platform and execute step D5. If there is a problem in the review, the administrator will return the change of institution application request information to the user for inspection;

[0064] Step D5: The platform receives the application for institution change after review by the institution to which the user intends to transfer or the request for implementing the transitional policy for institution change submitted by the user, and calls the smart contract user management interface to process the institution change information;

[0065] Step D6: The platform stores the processed organization change information in the status database;

[0066] Step D7: User organization change is successful.

[0067] In the transaction of digital assets, the digital asset trading platform relies on the alliance chain smart contract to integrate secure multi-party computing to build a privacy computing protocol, and adopts a combination of Paillier homomorphic encryption and Pedersen commitment to establish an asset transaction information verification mechanism to perform computational privacy and transaction information verification on the chain data, thereby realizing privacy protection of digital asset transactions;

[0068] The steps for protecting the privacy of digital asset transactions are as follows:

[0069] Step E1: The platform receives asset transaction data from the institution to which the asset belongs, satisfying data = data0 + data1;

[0070] Step E2: Calculate λ=lcm(p-1,q-1);

[0071] Step E3: Select So that it satisfies the formula: gcd(L(g λ modn 2 ),n)=1, where L(*) satisfies:

[0072] Step E4: Homomorphically encrypt asset transaction data: En(data) = g data r n modn 2 , where the random number r∈Z n ;

[0073] Step E5: Calculate En(data0) and En(data1) and perform homomorphic encryption on the asset data;

[0074] Step E6: Every time a transaction is completed, the calculation formula for supplementing the record of the original asset data is D(E(data0)·E(data1))=data0+data1=data;

[0075] Step E7: Get the decrypted asset data, the calculation formula is: Where * includes data, data0 and data1.

[0076] Wherein, data0 represents the original data of digital assets before the transaction occurs, data1 represents the data recording the information of both parties of the asset transaction and the transaction timestamp when the transaction occurs, and data represents the digital asset data after the transaction is completed; En(*) represents the encryption of digital asset data*, and Dec(x) represents the decryption of digital asset data*; p and q represent two independent unequal prime numbers of length 3, respectively, and n represents the product of two selected prime numbers; lcm represents the greatest common divisor calculation symbol, gcd represents the least common multiple calculation symbol, and mod represents the remainder operation symbol; λ represents the calculation result of the greatest common divisor; Indicates n 2 A non-negative integer multiple of g. is a non-negative integer in ; L(*) means to operate on data*; Z n represents the set of n-fold integers, r represents the set belonging to Z n An integer; E(*) and D(*) represent the ciphertext and plaintext of data* respectively.

[0077] The steps of the asset transaction information verification mechanism are:

[0078] Step F1: After the transaction is concluded, both parties of the digital asset transaction provide their respective signature information r1, r2;

[0079] Step F2: Obtain the hash value v of the encrypted asset information after the transaction is completed from the alliance chain network;

[0080] Step F3: Calculate the committed value C1 = r1*G + v*H of the asset seller and the committed value C2 = r2*G + v*H of the asset buyer;

[0081] Step F4: record the difference of the commitment value ΔC=C1-C2=(r1-r2)*G as the result of transaction verification, i.e., the verification code of the transaction;

[0082] Step F5: When both parties want to verify the authenticity of the transaction, they need to exchange their commitment values ​​C1 and C2.

[0083] Step F6: After obtaining the other party's commitment value, the difference calculation is performed. When the calculation result is consistent with the verification code of the transaction, the authenticity of the transaction is verified;

[0084] Where C1 represents the commitment value generated by the asset seller, C2 represents the commitment value generated by the asset buyer, ΔC represents the difference between the commitment values ​​of the two parties to the transaction; G and H are the generation points on a specific elliptic curve; v represents the hash value of the encrypted asset information En(data) after the transaction is completed; r1 represents the encrypted user signature information of the asset seller, and r2 represents the encrypted user signature information of the asset buyer.

[0085] The beneficial effects of adopting the above technical solution are:

[0086] The present invention provides a digital asset transaction and privacy protection method based on alliance chain multi-party computing. The present invention is applicable to the digital asset transaction scheme of the alliance chain, migrates and improves the digital asset transaction protocol of the public chain, stipulates the number and identity of nodes, avoids difficulty in reaching consensus, and improves the data processing rate; utilizes the alliance chain digital asset privacy protection of secure multi-party computing, optimizes and improves the privacy leakage problem of the alliance chain, reduces communication overhead, and improves performance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 This is a structural diagram of a digital asset trading platform in an embodiment of the present invention;

[0088] Figure 2 Schematic diagram of the transaction process of the digital asset trading platform in an embodiment of the present invention;

[0089] Figure 3 This is a data storage structure diagram of a digital asset trading platform in an embodiment of the present invention;

[0090] Figure 4 The figure is a schematic diagram of the creation and issuance structure of digital assets in an embodiment of the present invention;

[0091] Figure 5 Schematic diagram of the transaction process of digital assets in an embodiment of the present invention;

[0092] Figure 6 A schematic diagram of the process of recharging a user account and changing a user institution in an embodiment of the present invention;

[0093] Figure 7 This is a flow chart of privacy protection for digital asset transactions in an embodiment of the present invention. DETAILED DESCRIPTION

[0094] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0095] A digital asset transaction and privacy protection method based on alliance chain multi-party computing, implemented on a digital asset transaction platform, including a user client, a background server, and an alliance chain platform server;

[0096] The structure of the digital asset trading platform is as follows Figure 2 As shown, ordinary users submit asset information to the backend server for processing through the user client, or the asset information is reviewed by the institution administrator or super administrator; the processed asset data will be transferred to the corresponding institution node management and stored in the database under the corresponding institution; the alliance chain platform server is composed of digital asset smart contracts, blockchain nodes and member service nodes. The digital asset smart contract defines the data structure of users and assets, and stipulates the specific business processing rules for asset issuance, user registration and asset transactions, so that the system can realize the automatic execution of digital asset transactions; the blockchain node provides blockchain services, receives business requests from the transaction background and conducts transaction consensus; the member service node relies on the complete member identity management mechanism encapsulated by the alliance chain platform server to provide member identity information identification and management functions for the backend server.

[0097] like Figure 1 As shown; the super administrator maintains contracts and alliance organizations, uploads and deploys smart contracts, queries the historical records of smart contract deployment, and registers new alliance organizations and organization administrators in the digital asset trading platform;

[0098] The said institution administrator manages assets and ordinary users, and manages the ordinary user information, digital asset status, and transaction records of the institution;

[0099] The ordinary user registers and logs in through the digital asset trading platform, and conducts digital asset transactions within or across institutions on the digital asset trading platform;

[0100] The data storage of the digital asset trading platform is as follows: Figure 3As shown in the figure, the distributed ledger based on the alliance chain uses a state database to store digital asset information in the form of key-value pairs, and the change records of asset information are stored in the form of blocks on the blockchain, forming an unalterable chain data structure. The data structure includes two categories: user information and asset information; user information defines user account, authority, affiliated institution, and asset quantity information; digital asset information defines the ID, affiliated institution, owner, and asset name information of digital assets; considering the specificity and complexity of the attributes of digital asset information, in order to support more fine-grained asset management and transactions, the platform can fragment asset information and split asset information into multiple asset units according to attribute categories. Using data sharding technology, the data of multiple asset units after splitting is dispersed to multiple nodes or storage devices, reducing the load pressure of a single node, improving data storage efficiency and query performance, and ensuring the availability and fault tolerance of data storage.

[0101] The user client and backend server of the digital asset trading platform both include user management, contract management, asset management and transaction processing modules.

[0102] The user management module implements the functions of registration, recharge, and transaction record query information maintenance for institutions and ordinary users; the default setting is that the information of the super administrator is directly written into the transaction background and smart contract. The super administrator performs registration operations on the institutions newly joining the alliance and records the institutional information into the database; in the process of registering institutional administrators, it is necessary to extract the institutional ID and institutional administrator data and write them into the blockchain together; ordinary users directly submit a registration form application, which is reviewed by the background and submitted to the blockchain to complete the registration. After completing the registration, the account is recharged and the personal information is improved. When ordinary users want to change their institutions, the change must be completed after the approval of the original institution and the administrator of the new institution; if the institution wants to withdraw from the alliance chain network, it must notify all users in the institution to complete the transfer to the new institution within the specified time limit, and implement the copyright management policy of the original institution during the transition period. Users may reselect other institutions. It is expected that users who do not select new institutions will be changed to the state of no institution by default, and need to reapply to join the new institution to participate in asset trading, and will not enjoy the transition period execution policy.

[0103] The contract management module implements the functions of uploading, deploying and querying the deployment history of smart contract files. When specific business rules change, the smart contract program needs to be rewritten according to the new rules and deployed to the alliance chain platform through the super administrator; uploading smart contracts is the process of uploading the written contract program file to the file server and recording the version number and business type information to the database; deploying smart contracts is the process of calling the blockchain smart contract deployment interface to deploy the contract file to the alliance chain platform. After successful deployment, the alliance chain platform will use the new contract program for transaction processing; deployment history query is the super administrator querying the historical records of contract deployment based on the background database records;

[0104] The asset management module is responsible for the issuance and management of digital assets. The assets submitted by the creator user are allowed to be issued online after being reviewed and approved by the administrator of the institution. The institution administrator issues digital assets in the name of the institution. Once the asset information is released, it will not be allowed to be changed, and only transactions and transfers can be realized.

[0105] The transaction processing module is responsible for receiving transaction requests for intra-institutional transactions and cross-institutional transactions, performing request verification, and transmitting transaction requests, and providing feedback to the user after obtaining the processing results; wherein, before the cross-institutional transaction process is carried out, user information needs to be queried and verified on the blockchain to prevent users from maliciously attacking the system, such as sending a large number of false transactions to cause transaction congestion in the blockchain subsystem; during the cross-institutional transaction process, it is necessary to implement and deduct the relevant policies of the institution where the original owner of the digital asset is located regarding the asset management and maintenance fee rate.

[0106] In order to avoid the adverse impact of malicious trading behaviors on the reputation and technical level of the platform during the transaction processing, the digital asset trading platform stipulates and restricts the behaviors in the transaction process, including:

[0107] 1. The number of daily transactions of a single digital asset between ordinary users shall not exceed 3 times;

[0108] 2. In principle, the amount by which the asset seller adjusts the transaction price of a single digital asset shall not exceed 20% of the current price. When the price adjustment exceeds 20%, the seller must provide the asset seller’s institution management with a price adjustment explanation and materials, and obtain approval from the institution’s administrator.

[0109] 3. The asset seller may adjust the transaction price of a single digital asset no more than twice a month;

[0110] A digital asset transaction and privacy protection method based on alliance chain and secure multi-party computing is implemented based on the aforementioned digital asset transaction platform, specifically including the creation and issuance of digital assets, the transaction of digital assets, the recharge of user accounts and the change of user institutions, respectively. Figure 4 , Figure 5 , Figure 6 shown.

[0111] The creation and issuance of the digital assets specifically include the following steps:

[0112] Step A1: The asset creator submits digital asset issuance information to the administrator of the institution to which he belongs;

[0113] Step A2: After receiving the digital asset issuance information, the institution administrator will review it. If the issuance information is reviewed and found to be correct, step A3 will be executed. If there are problems with the issuance information review, the institution administrator will return the asset issuance information to the asset creator for revision. After the revision, step A1 will be executed.

[0114] Step A3: The institution administrator checks the issuance status of the digital asset issuance information. If the digital asset has not been issued, the institution administrator submits the digital asset issuance information to the platform. If the digital asset has been issued, the institution administrator returns the asset issuance information to the asset creator for re-modification. After the modification, execute step A1;

[0115] Step A4: After receiving the digital asset issuance information submitted by the institution administrator for review, the platform calls the smart contract asset management interface to process the asset issuance information;

[0116] Step A5: The platform stores the processed asset issuance information into the status database;

[0117] Step A6: Digital assets are issued successfully.

[0118] The transaction of the digital asset specifically includes the following steps:

[0119] Step B1: The asset owner or institution issues digital assets, and the asset buyer submits a purchase request to the platform;

[0120] Step B2: After receiving the asset purchase request submitted by the asset purchaser, the platform determines whether the asset purchaser and the institution to which the asset to be purchased belongs to the same institution; if they do, the platform transfers the intra-institutional transaction request and the asset purchase request to the institution to which the asset belongs and executes step B3; if they do not, execute step B4;

[0121] Step B3: After the institution to which the asset belongs receives the intra-institutional transaction request and asset purchase request transferred from the platform, it executes the digital asset transaction within the institution and executes step B5;

[0122] Step B4: Execute cross-institution digital asset transactions;

[0123] Step B4.1: The platform retrieves the cross-institutional transaction policy fee standard information of the institution to which the asset is purchased, and transfers the standard information, the cross-institutional transaction request and the asset purchase request to the institution to which the asset belongs;

[0124] Step B4.2: After the institution to which the asset belongs receives the cross-institutional transaction policy fee standard information, cross-institutional transaction request and asset purchase request transferred by the platform, it executes step B5;

[0125] Step B5: The institution to which the asset belongs checks whether the balance of the asset buyer's account is sufficient. If the balance meets the asset transaction price, step B6 is executed. If the balance does not meet the asset transaction price, the asset transaction fails and the user should recharge the account.

[0126] Step B6: The institution to which the asset belongs submits information such as the asset purchase request and transaction request to the platform;

[0127] Step B7: After receiving the asset request, transaction request and other information submitted by the institution to which the asset belongs, the platform calls the smart contract asset transaction interface to process the asset transaction information;

[0128] Step B8: The platform stores the processed asset transaction information into the status database;

[0129] Step B9: Digital asset purchase is successful.

[0130] The recharging of the user account specifically includes the following steps:

[0131] Step C1: The user submits an account recharge request to the platform to perform payment operations;

[0132] Step C2: The platform receives the account recharge request submitted by the user and waits for the payment result from the payment platform;

[0133] Step C3: When the payment result of the payment platform shows that the payment is successful, execute step C4; when the payment result of the payment platform shows that the payment fails, the account recharge fails;

[0134] Step C4: The platform calls the smart contract user management interface to process the account recharge request and payment success information;

[0135] Step C5: The platform stores the processed account recharge information into the status database;

[0136] Step C6: Account recharge is successful.

[0137] The change of the user organization specifically includes the following steps:

[0138] Step D1: User organization change application includes two situations, namely, ordinary users submit change applications, and execute step D1.1; organization withdrawal adjustment ordinary user organization change, execute step D1.2;

[0139] Step D1.1: The user submits an application for change of organization, that is, the user submits the application for change of organization to the administrator of the organization to which the user currently belongs, and executes step D3;

[0140] Step D1.2: When an institution applies to withdraw from the platform, it must reach an agreement with the institution that will take over the platform. The withdrawing institution will submit the agreement to the platform and execute step D2;

[0141] Step D2: After the exiting institution and the undertaking institution reach an agreement and submit it to the platform, execute steps D2.1, D2.2 and D2.3 in sequence;

[0142] Step D2.1: After receiving the agreement submitted by the exiting institution, the platform will file it and send the result of the filing completion to the exiting institution;

[0143] Step D2.2: After the exiting institution receives the record completion result from the platform, it will issue a notice to all users in the institution, and the users will choose to implement the transitional policy or apply for a change of institution;

[0144] Step D2.3: When the user chooses to implement the transitional policy, the user submits a request to the platform to change the transitional policy implementation agency, and executes step D5. When the user chooses to apply for agency change, execute step D1;

[0145] Step D3: After receiving the organization change request submitted by the user, the administrator of the current organization of the user will review whether the user meets the transfer-out conditions. If the review is passed, the administrator of the current organization of the user will transfer the organization change request to the organization to which the user intends to transfer, and execute step D4. If there is a problem in the review, the organization administrator will return the organization change request information to the user for inspection;

[0146] Step D4: After receiving the change of institution application request from the original institution of the user, the administrator of the institution to which the user intends to transfer will review whether the user meets the transfer-in conditions. If the review is passed, the administrator will submit the change of institution application request to the platform and execute step D5. If there is a problem in the review, the administrator will return the change of institution application request information to the user for inspection;

[0147] Step D5: The platform receives the application for institution change after review by the institution to which the user intends to transfer or the request for implementing the transitional policy for institution change submitted by the user, and calls the smart contract user management interface to process the institution change information;

[0148] Step D6: The platform stores the processed organization change information in the status database;

[0149] Step D7: User organization change is successful.

[0150] In the transaction of digital assets, the digital asset trading platform relies on the alliance chain smart contract to integrate secure multi-party computing to build a privacy computing protocol in order to ensure that the transaction data is processed without sharing the original data. The asset transaction information verification mechanism is established by combining Paillier homomorphic encryption and Pedersen commitment to verify the computational privacy and transaction information of the on-chain data, realize data processing, and ensure the confidentiality of the data and the authenticity and security of the transaction. Figure 7 shown.

[0151] The steps for protecting the privacy of digital asset transactions are as follows:

[0152] Step E1: The platform receives asset transaction data from the institution to which the asset belongs, satisfying data = data0 + data1;

[0153] Step E2: Calculate λ=lcm(p-1,q-1);

[0154] Step E3: Select So that it satisfies the formula: gcd(L(g λ modn 2 ),n)=1, where L(*) satisfies:

[0155] Step E4: Homomorphically encrypt asset transaction data: En(data) = g data r n modn 2 , where the random number r∈Z n ;

[0156] Step E5: Calculate En(data0) and En(data1) and perform homomorphic encryption on the asset data;

[0157] Step E6: Every time a transaction is completed, the calculation formula for supplementing the record of the original asset data is D(E(data0)·E(data1))=data0+data1=data;

[0158] Step E7: Get the decrypted asset data, the calculation formula is: Where * includes data, data0 and data1.

[0159] Wherein, data0 represents the original data of digital assets before the transaction occurs, data1 represents the data recording the information of both parties of the asset transaction and the transaction timestamp when the transaction occurs, and data represents the digital asset data after the transaction is completed; En(*) represents the encryption of digital asset data*, and Dec(x) represents the decryption of digital asset data*; p and q represent two independent unequal prime numbers of length 3, respectively, and n represents the product of two selected prime numbers; lcm represents the greatest common divisor calculation symbol, gcd represents the least common multiple calculation symbol, and mod represents the remainder operation symbol; λ represents the calculation result of the greatest common divisor; Indicates n 2 A non-negative integer multiple of g. is a non-negative integer in ; L(*) means to operate on data*; Z n represents the set of n-fold integers, r represents the set belonging to Z n An integer; E(*) and D(*) represent the ciphertext and plaintext of data* respectively.

[0160] The steps of the asset transaction information verification mechanism are:

[0161] Step F1: After the transaction is concluded, both parties of the digital asset transaction provide their respective signature information r1, r2;

[0162] Step F2: Obtain the hash value v of the encrypted asset information after the transaction is completed from the alliance chain network;

[0163] Step F3: Calculate the committed value C1 = r1*G + v*H of the asset seller and the committed value C2 = r2*G + v*H of the asset buyer;

[0164] Step F4: record the difference of the commitment value ΔC=C1-C2=(r1-r2)*G as the result of transaction verification, i.e., the verification code of the transaction;

[0165] Step F5: When both parties want to verify the authenticity of the transaction, they need to exchange their commitment values ​​C1 and C2. Although they have made their commitment values ​​public to each other, it is very difficult for others to calculate the r value and the original information v due to the characteristics of the elliptic curve.

[0166] Step F6: Since both parties know their own commitment values, they calculate the difference after obtaining the other party's commitment value. When the calculation result is consistent with the verification code of the transaction, the authenticity of the transaction is verified;

[0167] Where C1 represents the commitment value generated by the asset seller, C2 represents the commitment value generated by the asset buyer, ΔC represents the difference between the commitment values ​​of the two parties to the transaction; G and H are the generation points on a specific elliptic curve; v represents the hash value of the encrypted asset information En(data) after the transaction is completed; r1 represents the encrypted user signature information of the asset seller, and r2 represents the encrypted user signature information of the asset buyer.

[0168] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A digital asset transaction and privacy protection method based on alliance chain multi-party computing, characterized in that: Specifically, it includes the creation and issuance of digital assets, the trading of digital assets, the top-up of user accounts and the change of user institutions; The creation and issuance of the digital assets specifically include the following steps: Step A1: The asset creator submits digital asset issuance information to the administrator of the institution to which he belongs; Step A2: After receiving the digital asset issuance information, the institution administrator will review it. If the issuance information is reviewed and found to be correct, step A3 will be executed. If there are problems with the issuance information review, the institution administrator will return the asset issuance information to the asset creator for revision. After the revision, step A1 will be executed. Step A3: The institution administrator checks the issuance status of the digital asset issuance information. If the digital asset has not been issued, the institution administrator submits the digital asset issuance information to the platform. If the digital asset has been issued, the institution administrator returns the asset issuance information to the asset creator for re-modification. After the modification, execute step A1; Step A4: After receiving the digital asset issuance information submitted by the institutional administrator for review, the platform calls the smart contract asset management interface to process the asset issuance information; Step A5: The platform stores the processed asset issuance information into the status database; Step A6: Digital assets are issued successfully; The transaction of the digital asset specifically includes the following steps: Step B1: The asset owner or institution issues digital assets, and the asset buyer submits a purchase request to the platform; Step B2: After receiving the asset purchase request submitted by the asset purchaser, the platform determines whether the asset purchaser and the institution to which the asset to be purchased belongs to the same institution; if they do, the platform transfers the intra-institutional transaction request and the asset purchase request to the institution to which the asset belongs and executes step B3; if they do not, execute step B4; Step B3: After the institution to which the asset belongs receives the intra-institutional transaction request and asset purchase request transferred from the platform, it executes the digital asset transaction within the institution and executes step B5; Step B4: Execute cross-institution digital asset transactions; Step B5: The institution to which the asset belongs checks whether the balance of the asset buyer's account is sufficient. If the balance meets the asset transaction price, step B6 is executed. If the balance does not meet the asset transaction price, the asset transaction fails and the user should recharge the account. Step B6: The institution to which the asset belongs submits information such as the asset purchase request and transaction request to the platform; Step B7: After receiving the asset request, transaction request and other information submitted by the institution to which the asset belongs, the platform calls the smart contract asset transaction interface to process the asset transaction information; Step B8: The platform stores the processed asset transaction information into the status database; Step B9: Digital asset purchase is successful; The recharging of the user account specifically includes the following steps: Step C1: The user submits an account recharge request to the platform to perform payment operations; Step C2: The platform receives the account recharge request submitted by the user and waits for the payment result from the payment platform; Step C3: When the payment result of the payment platform shows that the payment is successful, execute step C4; when the payment result of the payment platform shows that the payment fails, the account recharge fails; Step C4: The platform calls the smart contract user management interface to process the account recharge request and payment success information; Step C5: The platform stores the processed account recharge information into the status database; Step C6: Account recharge is successful; The change of the user organization specifically includes the following steps: Step D1: User organization change application includes two situations, namely, ordinary users submit change applications, and execute step D1.1; organization withdrawal adjustment ordinary user organization change, execute step D1.2; Step D1.1: The user submits an application for change of organization, that is, the user submits the application for change of organization to the administrator of the organization to which the user currently belongs, and executes step D3; Step D1.2: When an institution applies to withdraw from the platform, it must reach an agreement with the institution that will take over the platform. The withdrawing institution will submit the agreement to the platform and execute step D2; Step D2: After the exiting institution and the undertaking institution reach an agreement and submit it to the platform, execute steps D2.1, D2.2 and D2.3 in sequence; Step D2.1: After receiving the agreement submitted by the exiting institution, the platform will file it and send the result of the filing completion to the exiting institution; Step D2.2: After the exiting institution receives the record completion result from the platform, it will issue a notice to all users in the institution, and the users will choose to implement the transitional policy or apply for a change of institution; Step D2.3: When the user chooses to implement the transitional policy, the user submits a request to the platform to change the transitional policy implementation agency, and executes step D5. When the user chooses to apply for agency change, execute step D1; Step D3: After receiving the organization change request submitted by the user, the administrator of the current organization of the user will review whether the user meets the transfer-out conditions. If the review is passed, the administrator of the current organization of the user will transfer the organization change request to the organization to which the user intends to transfer, and execute step D4. If there is a problem in the review, the organization administrator will return the organization change request information to the user for inspection; Step D4: After receiving the change of institution application request from the original institution of the user, the administrator of the institution to which the user intends to transfer will review whether the user meets the transfer-in conditions. If the review is passed, the administrator will submit the change of institution application request to the platform and execute step D5. If there is a problem in the review, the administrator will return the change of institution application request information to the user for inspection; Step D5: The platform receives the application for institution change after review by the institution to which the user intends to transfer or the request for implementing the transitional policy for institution change submitted by the user, and calls the smart contract user management interface to process the institution change information; Step D6: The platform stores the processed organization change information in the status database; Step D7: User organization change is successful.

2. According to claim 1, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: The step B4 specifically comprises the following steps: Step B4.1: The platform retrieves the cross-institutional transaction policy fee standard information of the institution to which the asset is purchased, and transfers the standard information, the cross-institutional transaction request and the asset purchase request to the institution to which the asset belongs; Step B4.2: After the institution to which the assets belong receives the cross-institutional transaction policy fee standard information, cross-institutional transaction request and asset purchase request transferred by the platform, it executes step B5.

3. According to claim 1, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: It is implemented based on a digital asset trading platform, which includes a user client, a backend server, and a consortium chain platform server; Ordinary users submit asset information to the backend server for processing through the user client, or the asset information is reviewed by the institution administrator or super administrator; the processed asset data will be transferred to the corresponding institution node management and stored in the database under the corresponding institution; the alliance chain platform server is composed of digital asset smart contracts, blockchain nodes and member service nodes. The digital asset smart contracts define the data structure of users and assets, and stipulate the specific business processing rules for asset issuance, user registration and asset transactions. The blockchain nodes provide blockchain services, receive business requests from the transaction background and conduct transaction consensus; the member service nodes rely on the complete member identity management mechanism encapsulated by the alliance chain platform server to provide member identity information identification and management functions for the backend server.

4. According to claim 3, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: The super administrator maintains contracts and alliance organizations, uploads and deploys smart contracts, queries the historical records of smart contract deployment, and registers new alliance organizations and organization administrators in the digital asset trading platform; The said institution administrator manages assets and ordinary users, and manages the ordinary user information, digital asset status, and transaction records of the institution; The ordinary users register and log in through the digital asset trading platform, and perform digital asset transactions within or across institutions on the digital asset trading platform.

5. According to claim 4, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: The digital asset trading platform relies on the distributed ledger of the alliance chain and uses a state database to store digital asset information in the form of key-value pairs. The change records of asset information are stored in the form of blocks on the blockchain. The data structure includes two types of user information and asset information. User information defines user account, authority, affiliated organization, and asset quantity information. Digital asset information defines the digital asset’s ID, organization, owner, and asset name information; Fragment the asset information and split it into multiple asset units according to attribute categories. Use data sharding technology to distribute the data of multiple asset units after splitting to multiple nodes or storage devices.

6. According to claim 3, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: The user client and backend server of the digital asset trading platform both include user management, contract management, asset management and transaction processing modules; The user management module implements the registration, recharge, and transaction record query information maintenance functions for institutions and ordinary users; the default setting is that the super administrator's information is directly written into the transaction background and smart contract. The super administrator performs registration operations on institutions newly joining the alliance and records the institution information into the database; in the process of registering institution administrators, it is necessary to extract the institution ID and institution administrator data and write them into the blockchain together; Ordinary users can directly apply by submitting a registration form, which will be reviewed by the backend and submitted to the blockchain to complete the registration. After completing the registration, they can recharge their accounts and complete their personal information. When ordinary users want to change their affiliated institutions, they must complete the change after approval by the administrators of the original and new institutions. If an institution wants to withdraw from the alliance chain network, it must notify all users in the institution to complete the transfer to the new institution within the specified time limit and implement the copyright management policy of the original institution during the transition period. Users may reselect other institutions. It is expected that users who do not select new institutions will be defaulted to the state of no institution and need to reapply to join the new institution to participate in asset transactions, and will not enjoy the transition period execution policy. The contract management module implements the functions of uploading, deploying and querying the deployment history of smart contract files. When specific business rules change, the smart contract program needs to be rewritten according to the new rules and deployed to the alliance chain platform through the super administrator. Uploading a smart contract is the process of uploading the written contract program file to the file server and recording the version number and business type information into the database; Deploying smart contracts is the process of calling the blockchain smart contract deployment interface to deploy the contract file to the alliance chain platform. After successful deployment, the alliance chain platform will use the new contract program to process transactions; Deployment history query is the process of super administrators querying the contract deployment history records based on the background database records; The asset management module is responsible for the issuance and management of digital assets. The assets submitted by the creator user are allowed to be issued online after being reviewed and approved by the administrator of the institution. The administrator of the institution issues digital assets in the name of the institution. Once the asset information is released, it will not be allowed to be changed, and only transactions and transfers can be realized. The transaction processing module is responsible for receiving transaction requests for intra-institutional transactions and cross-institutional transactions, performing request verification, and transmitting transaction requests, and providing feedback to the user after obtaining the processing results; wherein, before the cross-institutional transaction process is carried out, user information needs to be queried and verified on the blockchain, and during the cross-institutional transaction process, it is necessary to implement and deduct the relevant policies of the institution where the original owner of the digital asset is located regarding the asset management and maintenance fee rate.

7. According to claim 3, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: The digital asset trading platform stipulates and restricts the behaviors in the trading process, including: (1) The number of transactions per day between ordinary users for a single digital asset shall not exceed 3 times; (2) In principle, the amount by which the asset seller adjusts the transaction price of a single digital asset shall not exceed 20% of the current price. If the price adjustment exceeds 20%, the seller must provide the asset seller’s institution management with a price adjustment explanation and materials, and obtain approval from the institution management; (3) The asset seller may adjust the transaction price of a single digital asset no more than twice per month.

8. According to claim 3, a digital asset transaction and privacy protection method based on alliance chain multi-party computing is characterized in that: In the transaction of digital assets, the digital asset trading platform relies on the alliance chain smart contract to integrate secure multi-party computing to build a privacy computing protocol, and adopts a combination of Paillier homomorphic encryption and Pedersen commitment to establish an asset transaction information verification mechanism to perform computational privacy and transaction information verification on the chain data, thereby realizing privacy protection of digital asset transactions.

9. A digital asset transaction and privacy protection method based on alliance chain multi-party computing according to claim 8, characterized in that: The steps for protecting the privacy of digital asset transactions are as follows: Step E1: The platform receives asset transaction data from the institution to which the asset belongs, satisfying data = data0 + data1; Step E2: Calculate λ=lcm(p-1,q-1); Step E3: Select So that it satisfies the formula: gcd(L(g λ modn 2 ),n)=1, where L(*) satisfies: Step E4: Homomorphically encrypt asset transaction data: En(data) = g data r n modn 2 , where the random number r∈Z n ; Step E5: Calculate En(data0) and En(data1) and perform homomorphic encryption on the asset data; Step E6: Every time a transaction is completed, the calculation formula for supplementing the record of the original asset data is D(E(data0)·E(data1))=data0+data1=data; Step E7: Get the decrypted asset data, the calculation formula is: Where * includes data, data0 and data1; Wherein, data0 represents the original data of digital assets before the transaction occurs, data1 represents the data recording the information of both parties of the asset transaction and the transaction timestamp when the transaction occurs, and data represents the digital asset data after the transaction is completed; En(*) represents the encryption of digital asset data*, and Dec(x) represents the decryption of digital asset data*; p and q represent two independent unequal prime numbers of length 3, respectively, and n represents the product of two selected prime numbers; lcm represents the greatest common divisor calculation symbol, gcd represents the least common multiple calculation symbol, and mod represents the remainder operation symbol; λ represents the calculation result of the greatest common divisor; Indicates n 2 A non-negative integer multiple of g. is a non-negative integer in ; L(*) means to operate on data*; Z n represents the set of n-fold integers, r represents the set belonging to Z n An integer; E(*) and D(*) represent the ciphertext and plaintext of data* respectively.

10. A digital asset transaction and privacy protection method based on alliance chain multi-party computing according to claim 8, characterized in that: The steps of the asset transaction information verification mechanism are: Step F1: After the transaction is concluded, both parties of the digital asset transaction provide their respective signature information r1, r2; Step F2: Obtain the hash value v of the encrypted asset information after the transaction is completed from the alliance chain network; Step F3: Calculate the committed value C1 = r1*G + v*H of the asset seller and the committed value C2 = r2*G + v*H of the asset buyer; Step F4: record the difference of the commitment value ΔC=C1-C2=(r1-r2)*G as the result of transaction verification, i.e., the verification code of the transaction; Step F5: When both parties want to verify the authenticity of the transaction, they need to exchange their commitment values ​​C1 and C2. Step F6: After obtaining the other party's commitment value, the difference calculation is performed. When the calculation result is consistent with the verification code of the transaction, the authenticity of the transaction is verified; Where C1 represents the commitment value generated by the asset seller, C2 represents the commitment value generated by the asset buyer, ΔC represents the difference between the commitment values ​​of the two parties to the transaction; G and H are the generation points on a specific elliptic curve; v represents the hash value of the encrypted asset information En(data) after the transaction is completed; r1 represents the encrypted user signature information of the asset seller, and r2 represents the encrypted user signature information of the asset buyer.

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